U.S. Pat. No. 6,127,621 entitled Power Sphere, U.S. Pat. No. 6,284,966 entitled Power Sphere Nanosatellite, U.S. Pat. No. 6,396,167 entitled Power Distribution System, U.S. Pat. No. 6,318,675 entitled Power Sphere Deployment Method, and U.S. Pat. No. 6,300,158 entitled Integrated Solar Power Module, all of which are hereby incorporated by reference, teach the use of solar cells for powering a spacecraft. The connections between individual serially connected solar cells and serial strings of solar cells have been accomplished by soldering or welding interconnect conductors to the front and back contacts of the solar cells. Solar cells use wire or wire mesh interconnects to connect individual solar cells in a series or to serially connect strings of solar cells to a spacecraft power bus. However, solder and mesh interconnections disadvantageously add significant mass to the thin film structure.
Thin film solar cells can be fabricated using monolithically integrated interconnections that eliminate the need for separate interconnect conductors for connecting a string of solar cells in series. Monolithically interconnected serial strings of thin film solar cells are readily available in commercial markets. Conventional thin film solar cells can be monolithically interconnected in thin film solar cell modules, but ultimately require connection to the spacecraft power bus disadvantageously using welding or soldering interconnects between the module and the power bus. The interconnects are typically made by soldering or welding methods to make electrical connections between the solar cells and the power bus. These welding and soldering methods of interconnection are not well suited for sensitive thin film structures due to excessive spot heat. That is, welding or soldering requires a high temperature to melt the solder or to weld a contact. This high temperature may be significantly higher than the maximum temperature that the thin film solar cell can withstand without damage during fabrication. Hence, another problem of connecting monolithically integrated thin film solar cells is the use of hot welding and soldering methods for interconnecting the thin film solar cells to the spacecraft power bus.
U.S. Pat. Nos. 6,284,966, and 6,318,675, and 6,127,621 teach stowing and deploying a stack of hexagons and pentagons to form a geodetic sphere as a power sphere spacecraft. The flat hexagonal and pentagonal panels are thin film solar cell panels that form a power sphere. Inflatable hinges are flexible tubular hinges used to precisely position the individual panels from a stowed position into final deployed positions forming the sphere of panels. One problem associated with flexible inflatable hinges is the need for routing power produced by the thin film solar cell panels across the hinges to the power bus.
The inflatable hinges are flexible for enabling inflation using sublimation powders for deploying space structures. The inflatable hinges do not form a rigid structure after the deployment is complete. It is desirable to rigidize the positions of the panels for accurately and rigidly forming the power sphere. Mechanical hinges can be used for rigidizing the position of the panels after deployment. However, mechanical deployment hinges disadvantageously add significant mass and control complexity to the spacecraft. Also, electrical conductors that cross the hinges are bundled together causing twisting and stresses that may lead to breakage of the conductors. Also, mechanical hinges disadvantageously require variable sizes to accommodate variable stacking thicknesses of the panels. These and other disadvantages are solved or reduced using the invention.